How do squid and octopus get their big brains?

Cephalopods, including octopuses, cuttlefish, and their cuttlefish cousins, are capable of very interesting behaviors. They can quickly process information to change shape, color, and even texture and blend it into their surroundings. They can also communicate, show signs of spatial learning, and use tools to solve problems. They are highly intelligent and can even get bored.

It’s no secret what makes it possible: Cephalopods have the most complex brains of any invertebrate on the planet. But what is still a mystery is the development process. Basically, scientists have always wondered how this happened cephalopod First, make their brains big. The Harvard lab that studied the visual system of these soft-bodied creatures – where two-thirds of the central computing network is concentrated – thought they almost found it. They say the process sounds very familiar.

In a study published in current biology, researchers at the FAS Center for Systems Biology explain how they used new live imaging technology to examine neurons created in embryos in the near future. Then they were able to trace those cells through the development of the nervous system in the retina. What they saw shocked them.

It neural stem cells They monitored behavior very similar to how these cells behaved in vertebrates during the development of their nervous system. He suggested that vertebrates and cephalopods, although different from each other 500 million years ago, not only used similar mechanisms to create their brains, but that the processes and ways in which cells function, divide and form can basically determining patterns that require the development of this type of system, this nerve.

“Our conclusions are surprising, because much of what we know about the development of the nervous system in vertebrates has long been thought to be strange in this lineage,” said Christine Koenig, a researcher at Harvard University and senior author of the study.

“Given the fact that the processes are very similar, what it is suggesting to us is that these two systems have independently developed very large nervous systems that use the same mechanisms to build them. This suggests that the mechanism, the tool, that animals use during development may be important for the construction of buildings. “Excellent nervous system.

Scientists from the Koenig lab focused on the retina of a squid called Doryteuthis pealeii, better known as a type of longfin squid. Squid grow to nearly a foot in length and are abundant in the northwestern Atlantic Ocean. As fetuses, they look good, with large heads and large eyes.

The researchers used techniques similar to those that have become widespread to study model organisms, such as fruit flies and zebrafish. They created special tools and used state-of-the-art microscopes that could acquire high-resolution images every ten minutes for hours to see how individual cells behaved. The researchers used fluorescent dyes to mark the cells so they could be mapped and tracked.

This live imaging technology allowed the team to track called stem cells ancestral neuronsand how it is organized. The cells form a special type of structure called a pseudostratified epithelium. Its main advantage is that the cells are stretched so that they can be compacted. The researchers also noted that the core of this structure moved up and down before and after mitosis. This movement is important for keeping the network organized and for continued growth, they say.

This type of structure is universal in how vertebrate species develop their brains and eyes. Historically, it has been considered one of the reasons the vertebrate nervous system has grown so large and complex. Scientists have observed examples of this type of neuroepithelium in other animals, but squid The tissue they saw in this case was very similar to that of vertebrates in size, organization and appearance. inti he moved.

The research was conducted by Francesca R. Naples and Christina M. Daly, research assistants in Koenig’s laboratory.

Next, the lab plans to examine what different cell types look like in the cephalopod brains. Koenig wanted to determine whether they are expressed at different times, how they decide to become one type of neuron over another, and whether these actions are similar between species.

Konig is excited about the potential discoveries that lie ahead.

“One of the most important things to learn from this type of work is how important it is to study the diversity of life,” said Koenig. “By studying this diversity, you can really get back to the basic idea of ​​our development and our questions related to biomedicine. You can absolutely talk about this question.